Cleaning fluid apparatus and method for continuous printing ink-jet nozzle

Abstract

A fluid (liquid or water) wash is used to clean the front surface of an ink jet printer cartridge. In addition, a nozzle plate that overlies the nozzle shields the nozzle array from the splatter of ink. In ink jet printers, ink droplets are propelled from an array of orifices in a nozzle plate in the printer head. During the ink droplet ejection, ink is sprayed or deposited around the orifices. The ink droplets are deposited on a paper web adjacent the nozzle and mist from the droplets drifts back to coat the face of the nozzle plate. Some ink seeps behind the nozzle plate onto the array of nozzle orifices. The ink coating attracts particles that tend to clog the nozzle orifices. The ink coating is washed away by fluid streams that flow over the nozzle surface and in some embodiments flow over the nozzle orifices themselves. The fluid may be water, ink or other liquid that is channelled across the nozzle surface, or the fluid may be an air stream that blows across the nozzle surface.

What is claimed is: 
     
       1. An ink jet printer head comprising: a. an array of nozzle orifices through which ink droplets are projected in a path towards a substrate for printing and a front surface of said array of nozzle orifices having channels passing between the orifices;   b. a nozzle plate disposed between said array of nozzle orifices and the substrate and separated by a gap from the array, said nozzle plate having a slit aligned with respect to the path to allow the ink droplets to fly through the slit, and   c. a liquid cleaning fluid stream flowing in the channels of the front surface, and through the gap between the nozzle plate and array of nozzle orifices, wherein said liquid fluid stream flows while ink droplets are being projected from the nozzle orifices during printing.   
     
     
       2. An ink jet printer head as in claim 1 wherein the slit in the nozzle plate has an area that is slightly larger than an area of said array of nozzle orifices. 
     
     
       3. An ink jet printer head as in claim 1 wherein said nozzle plate is formed of an ink adsorbent, porous material. 
     
     
       4. An ink jet printer comprising: a. an ink jet printer head having a front surface and an array of nozzle orifices arranged on the front surface, wherein ink droplets are projected through the orifices along a path towards a substrate;   b. a bracket having a recess adapted to receive the ink jet printer head;   c. a mounting plate removably attached to said bracket and securing said ink jet printer head in the recess, said mounting plate having an opening into which projects the front surface of the ink jet printer heads;   d. a nozzle plate attached to said mounting plate and covering the opening in the mounting plate and separated by a gap from the front surface the ink jet printer head, wherein said nozzle plate having a slit aligned with the array of nozzle orifices and through which pass ink jet droplets on their path, and   e. a liquid cleaning fluid stream flowing in the gap between the nozzle plate and front surface of the printer head, wherein said liquid fluid stream flows adjacent to the nozzle orifices while ink droplets are projected from the nozzle orifices to the substrate.   
     
     
       5. An ink jet printer head as in claim 4 further comprising a cleaning fluid stream flowing across the front surface of the ink jet printer head. 
     
     
       6. An ink jet printer head as in claim 4 wherein said nozzle plate has a front surface facing the substrate and a rear surface facing the printer head, and said nozzle plate is porous such that ink splattered on the front surface is drawn through the nozzle plate and washed away by the liquid cleaning fluid stream. 
     
     
       7. An ink jet printer as in claim 4 further comprising a second liquid fluid stream on a front surface of the nozzle plate facing the substrate and wherein at least a portion of the second liquid fluid stream is drawn through the slit in the nozzle plate to merge with the liquid cleaning fluid stream. 
     
     
       8. An in jet printer as in claim 4 wherein said front surfaces of said printer head is furrowed with channels for the liquid cleaning fluid stream(s). 
     
     
       9. An ink jet printer as in claim 8 wherein said channels are coated with a hydrophilic material. 
     
     
       10. An ink jet printer as in claim 4 wherein the gap between the front surface of the ink jet printer head and the nozzle plate widens to form a reservoir below the array of nozzle orifices. 
     
     
       11. An ink jet printer as in claim 4 further comprising a suction opening in said bracket and located below the array of nozzle orifices and said suction opening having a slight vacuum for drawing excess ink from the gap between the ink jet printer head and the nozzle plate. 
     
     
       12. An ink jet printer as in claim 4 further comprising a suction opening in said bracket and located below the array of nozzle orifices and said suction opening having a slight vacuum for drawing in the liquid fluid stream after the stream washes across the front surface of the printer head. 
     
     
       13. An ink jet printer as in claim 12 wherein said nozzle plate includes an opening aligned with the suction opening in the bracket and liquid fluid flowing over the nozzle plate is drawn into the opening in the plate and further into the suction opening. 
     
     
       14. A method for cleaning an ink jet printing head having a front surface with a nozzle array of orifices, and a nozzle plate separated by a gap from the front surface of the printing head, the method comprising the following steps: a. propelling ink from the nozzle array through a slit in the nozzle plate and towards a web for printing on the web;   b. shielding the orifices from ink splatter and airborne fibers and particles with the nozzle plate;   c. washing the front surface of the printing head with a liquid fluid stream while propelling ink during step (a), and   d. draining the liquid fluid stream and excess ink on the nozzle array down through the gap between the front surface of the printing head and nozzle plate.   
     
     
       15. A method for cleaning an ink jet printing head as in claim 14 wherein the nozzle plate includes a channel adjacent the orifices and step (c) is further practiced by flowing the liquid fluid stream through the channel in the nozzle plate. 
     
     
       16. A method for cleaning an ink jet printing head as in claim 14 wherein step (c) further includes washing a front surface of the nozzle plate with a liquid fluid stream and drawing a portion of the liquid fluid stream across the nozzle plate through the slit in the nozzle plate.